Naches Bull Trout Population Group

Overview

The Naches Population Group consists of three fluvial bull trout populations. Detailed information on each can be found here:

American River Bull Trout Population

Crow Creek Bull Trout Population

Rattlesnake Creek Bull Trout Population

These three populations make use of shared foraging, migration, and overwintering (FMO) habitat in the Naches River, and historically may have mixed with Upper Yakima and Tieton River populations before dams blocked migration corridors in the early 1900s. Naches fluvial bull trout may also utilize the mainstem Yakima river upstream and downstream of the confluence with the Naches River when temperatures are suitable. Information on conditions, threats and actions for this shared FMO habitat are detailed in the Naches River FMO Habitat page.

Population Monitoring

There is limited evidence of movement outside of the Naches River although one fish tagged during the WDFW radio telemetry study (Mizell and Anderson 2010) moved into the Yakima River and one bull trout sampled at Roza Dam (RM 205.9) genetically assigned back to Rattlesnake Creek (Small and Martinez 2011). The contribution to the Naches River fluvial populations from fish entrained out of Rimrock and Bumping reservoirs is largely unknown but appears to occur to some limited extent; two of 13 adult bull trout trapped in 2003 after spawning in Rattlesnake Creek assigned to the South Fork Tieton River population, evidence that entrained fish may be contributing to Naches River fluvial bull trout populations (Small and Martinez 2011). These populations, however, remain distinct from populations above the reservoirs, indicating that one-way gene flow since the time of dam construction (~100 years) is not homogenizing populations (Small et al. 2009).

Note Little Naches potential population area and link to page; cite scott ppt/future report

Note Cowiche controversy- not further addressed as BT populaiton areas